Chirality at the molecular level is found in diverse biological structures, such as polysaccharides, proteins and DNA, and is responsible for many of their unique properties.
Introducing chirality into porous inorganic solids may produce new types of materials that could be useful for chiral separation, stereospecific catalysis, chiral recognition (sensing) and photonic materials. Template (structure directing agent) synthesis of inorganic solids using the self-assembly of lyotropic liquid crystals offers access to materials with well-defined porous structures, but only recently has chirality been introduced into hexagonal porous structures through the use of a chiral surfactant.
The development of a photonic mesoporous inorganic solid that is a cast of a chiral nematic liquid crystal formed from nanocrystalline cellulose is described by Shopsowitz K E et al. in Nature. 2010 Nov. 18; 468(7322):422-5.
U.S. Pat. No. 8,623,237 describes a composition and a method for producing mesoporous silica materials with a chiral organization wherein a polymerizable inorganic monomer is reacted in the presence of nanocrystalline cellulose (NCC) to give a material of inorganic solid with cellulose nanocrystallites embedded in a chiral nematic organization. The NCC can be removed to give a stable porous structure that retains the chiral organization of the NCC template.
U.S. Pat. No. 7,816,435 describes halo-functional silane and process for preparation thereof and, rubber composition containing same and articles manufactured therefrom.
The synthesis and application of silicon-stereogenic silanes by Li-Wen Xu, is disclosed in Chem. Soc. Rev., 2011, 40, 1777-1790. Further the preparation of “Si-centered” chiral silanes by direct α-lithiation of methylsilanes chemistry is reported by Dr. Christian Däschlein in European Journal vol. 16, (13), Pages 4048-4062, Apr. 6, 2010.
Recently Shunai Che et al. in Nature 429, 281-284 (20 May 2004) has reported templating route for preparing well-ordered mesoporous silicas based on the self-assembly of chiral anionic surfactants and inorganic precursors by using aminosilane or quaternized aminosilane as a co-structure-directing agent (CSDA), which is provided a potential method to synthesize mesoporous materials with inherent chirality.
WO0112564 relates to crystalline inorganic-organic oxide composition which are functionalized using organo silane and to the process of synthesis thereof. The process comprises reacting an inorganic oxide precursor and a hydrolyzable organic silane in the presence of water and a structure directing template having a hydrophobic and hydrophilic moiety to provide the composition.
US20040267038 relates to a mesoporous silica utilizing the structure of a self-assembled anionic surfactant as the template, characterized by using a basic silane, and a process for producing the same. The organo alkoxy silane with quaternary ammonium organic group (N-trimethoxylsilylpropyl-N,N,N-tributylammounium) has been used as the structure directing agent of zeolites ZSM-5 and ZSM-11. The hydrothermal process disclosed in US '038 comprises reacting an organo silane, a silicon precursor and anionic surfactant and washing with an acidic aqueous solution, a water-miscible organic solvent, or an aqueous solution or calcination to remove the anionic surfactant.
Functionalization of mesoporous silicas by incorporating heteroatoms either in the pore wall or on the pore surface or by anchoring organic groups onto their surface to create active sites for catalysis, selective adsorption, and separation is disclosed in article titled ‘Functionalized periodic mesoporous organosilicas for catalysis’ by Qihua Yang et al. in J. Mater. Chem., 2009, 19, 1945-1955.
U.S. Pat. No. 6,713,643 relates to mesostructured and microporous to mesoporous organo functionalized silica compositions. The compositions incorporate the organo functional group L as part of LSiO3 unit in the framework of the compositions. In addition the compositions incorporate the organo functional group R as part of O3Si—R—SiO3 unit in the framework of the compositions. The compositions are useful as molecular sieves, supports for catalysts and numerous other applications requiring an organo group on surfaces of silica.
With a view that, introducing molecular level chirality in to the silica framework can give rise to enormous possibilities for tuning the characters of chiral composition which can widen its scope in industrial applications, the present inventors felt a need to provide novel chiral composition by introduction of molecular level chirality into silica framework of crystalline mesoporous or microporous material.